阅读说明：本技术 一种Ag/NiS/TiO2纳米光阳极复合膜及其应用 (Ag/NiS/TiO2Nano photo-anode composite film and application thereof ) 是由 王宁 王静 刘梦楠 段继周 侯保荣 戈成岳 张冉 舒向泉 贺永鹏 林建康 乔泽 于 2020-12-24 设计创作，主要内容包括：本发明涉及纳米复合膜光阳极材料,尤其是涉及一种浸渍-沉积法和光还原法制备的光阳极复合膜(Ag/NiS/TiO-2光阳极复合膜)及其应用。先采用浸渍-沉积法将NiS纳米粒子复合到钛片基体的TiO-2纳米线表面,再采用光还原法将Ag纳米粒子复合到NiS/TiO-2纳米材料表面,形成Ag/NiS/TiO-2纳米光阳极复合膜。该复合膜作为光阳极材料进行阴极保护时,相比纯TiO-2材料而言,显著提高了TiO-2对可见光的利用率和光生电子-空穴对的分离率,降低了304不锈钢的电极电位,降低了腐蚀速率,有效提升了TiO-2对304不锈钢的光生阴极保护性能。(The invention relates to a nano composite film photo-anode material, in particular to a photo-anode composite film (Ag/NiS/TiO) prepared by a dipping-deposition method and a photo-reduction method 2 Photoanode composite film) and applications thereof. Firstly adopting an impregnation-deposition method to compound NiS nano particles to TiO of a titanium sheet substrate 2 Compounding Ag nanoparticles onto the surface of the nano-wire by adopting a photo-reduction method 2 Forming Ag/NiS/TiO on the surface of the nano material 2 A nano photo-anode composite film. When the composite film is used as a photo-anode material for cathode protection, compared with pure TiO 2 For materials, the TiO content is obviously improved 2 The utilization rate of visible light and the separation rate of photo-generated electron-hole pairs are reduced, and the 304 stainless steel is reducedThe electrode potential of the steel reduces the corrosion rate and effectively improves TiO 2 Photoproduction cathodic protection performance on 304 stainless steel.)

1. Ag/NiS/TiO₂The nano photo-anode composite film is characterized in that:firstly adopting an impregnation-deposition method to compound NiS nano particles to TiO of a titanium sheet substrate₂Compounding Ag nanoparticles onto the surface of the nano-wire by adopting a photo-reduction method₂Obtaining Ag/NiS/TiO on the surface of the nano material₂A nano photo-anode composite film.

2. Ag/NiS/TiO according to claim 1₂The nano photo-anode composite film is characterized in that: loading TiO on the surface₂Sequentially dipping the titanium sheet of the nanowire in an ethanol solution of nickel nitrate and a methanol-water mixed solution of sodium sulfide (the volume ratio is methanol: water is 1:1), and obtaining NiS/TiO through dipping-deposition₂A nanocomposite film material; wherein, the concentration of nickel nitrate in the ethanol is 0.03-0.05M, and the concentration of sodium sulfide in the methanol-water mixed solution is 0.03-0.05M.

3. Ag/NiS/TiO according to claim 2₂The nano photo-anode composite film is characterized in that: the NiS/TiO₂Placing the nano composite membrane material in 0.01-0.2M AgNO₃In the solution, ultraviolet light is used for irradiating and photoreduction is carried out for 0.5-1 h, and Ag/NiS/TiO can be obtained₂A nanocomposite film.

4. Ag/NiS/TiO according to claim 1₂The nano photo-anode composite film is characterized in that: the method comprises the steps of adopting a traditional double-electrode system, taking a titanium sheet as a working electrode, taking a platinum electrode as a counter electrode, clamping the counter electrode by an electrode clamp, putting the counter electrode into 2-3M NaOH solution, carrying out anodic oxidation, taking out the titanium sheet, washing the titanium sheet, putting the washed titanium sheet into a muffle furnace, setting the temperature in the furnace to be 450-600 ℃, calcining for 120-180 min, naturally cooling, and obtaining TiO on a titanium sheet substrate₂A nanowire.

5. The Ag/NiS/TiO of claim 1₂The application of the nano photo-anode composite film is characterized in that: the Ag/NiS/TiO₂The nanometer photo-anode composite film is used as a photo-anode material and applied to photo-cathode protection.

6. According toAg/NiS/TiO according to claim 5₂The application of the nano photo-anode composite film is characterized in that: the Ag/NiS/TiO₂The nanometer photo-anode composite film is applied to inhibiting metal corrosion as an anti-corrosion protective film.

Technical Field

The invention relates to a nano composite film photo-anode material, in particular to a photo-anode composite film (Ag/NiS/TiO) prepared by a dipping-deposition method and a photo-reduction method₂Photoanode composite film) and applications thereof.

Background

The corrosion of a large amount of metal materials in the using process not only causes huge economic loss and brings severe environmental pollution and energy consumption, but also can be a main cause of a plurality of disastrous accidents. The ocean environment is complex and severe, the salt content of the seawater is high, the chloride ion concentration is high, oxygen is enriched, a large number of microorganisms exist, and the electrochemical corrosion of the steel structure in the ocean environment is particularly serious due to the impact of sea waves and strong sunlight stimulation, so that the research and development of a new metal corrosion resisting technology are very important for various scholars, and the electrochemical protection technology for corrosion protection of metals is widely applied to the protection of industries such as ocean buildings, ships, underground steel and the like.

The photoproduction cathodic protection technology is a corrosion protection technology for converting solar energy into electrochemical energy required by metal corrosion, and the used material is not consumed in the process of protecting metal, has the characteristics of high efficiency and long service life, and is widely researched and applied. In the technology, an n-type semiconductor photo-anode and a protected metal are coupled and are placed in an electrolyte, when the photo-anode is irradiated by incident light with a proper wavelength, separated electrons and holes are generated through excitation, if the potential of photo-electrons is more negative than the self-corrosion potential of the metal, the photo-electrons can be transferred to the metal, and the potential of the metal is polarized towards the cathode, so that the purpose of cathodic protection is achieved.

At present, TiO₂The method has the characteristics of low price and high quantum conversion efficiency, and is always the focus of research on photoelectrochemistry cathode protection technology. However, TiO₂The potential of the conduction band of the metal is positive, the metal can only provide the photoelectrochemical cathode protection effect for the metal which is more positive in self-corrosion potential and is not easy to corrode, and the metal which is more negative in self-corrosion potential and easy to corrode cannot be protected. Therefore, it is necessary to develop materials with more negative conduction band potential and valence band potential capable of realizing water oxidation, and to apply the materials to the field, and realize photoelectrochemical cathodic protection on metals with more negative self-corrosion potential.

Disclosure of Invention

The invention aims to provide a photo-anode composite film (Ag/NiS/TiO) prepared by a dipping-deposition method and a photo-reduction method₂Photoanode composite film) and applications thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

Ag/NiS/TiO₂The nanometer photo-anode composite film is prepared by compounding NiS nanometer particles to TiO of titanium sheet substrate by dipping-deposition method₂Compounding Ag nanoparticles onto the surface of the nano-wire by adopting a photo-reduction method₂Forming Ag/NiS/TiO on the surface of the nano material₂A nano photo-anode composite film.

Further, the surface is supported with TiO₂The titanium sheet of the nanowire was sequentially immersed in an ethanol solution of nickel nitrate and a methanol-water mixed solution of sodium sulfide (methanol: water ═ 1:1), and was subjected to immersion-deposition to obtain NiS/TiO₂A nanocomposite film material; wherein the concentration of nickel nitrate in the ethanol is 0.03-0.05M, and sulfur in the methanol-water mixed solutionThe concentration of sodium is 0.03-0.05M.

The NiS/TiO₂Placing the nano composite membrane material in 0.01-0.2M AgNO₃In the solution, ultraviolet light is used for irradiating and photoreduction is carried out for 0.5-1 h, and Ag/NiS/TiO can be obtained₂A nanocomposite film.

Further, the method comprises the following steps:

(1) dissolving 0.03-0.05M of nickel nitrate in ethanol, dissolving for 20-30 min under magnetic stirring to prepare an ethanol solution of nickel nitrate, and then preparing a methanol-water mixed solution of 0.03-0.05M of sodium sulfide (methanol: water is 1:1) for later use;

(2) loading TiO on the surface₂Putting the titanium sheet of the nanowire into an ethanol solution of nickel nitrate, taking out after 2-4 min, quickly washing for 1-2 min by using a pure ethanol solution, and naturally drying; then putting the titanium sheet into a methanol-water mixed solution of sodium sulfide, taking out after 4-8 min, quickly washing for 1-2 min by using the methanol-water mixed solution, and naturally drying; finally, setting different deposition cycle times, placing the mixture into a muffle furnace vacuum system, setting the temperature to be 380-500 ℃, calcining for 10-20 min, cooling to room temperature and drying to obtain the NiS/TiO₂A nano composite film material.

Ag nano particles are loaded on NiS/TiO by adopting a photo-reduction method₂On the surface of the nano composite film, adding NiS/TiO₂The nano composite materials are respectively placed in 0-0.2 MAGNO₃In the solution, a sample is taken out after ultraviolet light irradiation is carried out for 0.5-1 h, the surface of the sample is washed clean by deionized water, and the sample is naturally dried, so that the Ag/NiS/TiO is obtained₂A nanocomposite film.

The method comprises the steps of adopting a traditional double-electrode system, taking a titanium sheet as a working electrode, taking a platinum electrode as a counter electrode, clamping the counter electrode by an electrode clamp, putting the counter electrode into 2-3M NaOH solution, carrying out anodic oxidation, taking out the titanium sheet, washing the titanium sheet, putting the washed titanium sheet into a muffle furnace, setting the temperature in the furnace to be 450-600 ℃, calcining for 120-180 min, naturally cooling, and obtaining TiO on a titanium sheet substrate₂A nanowire.

Ag/NiS/TiO₂Application of nano photo-anode composite film, Ag/NiS/TiO₂Application of nano photo-anode composite film as photo-anode material in photo-cathode protection。

The Ag/NiS/TiO₂The nanometer photo-anode composite film is applied to inhibiting metal corrosion as an anti-corrosion protective film.

For the Ag/NiS/TiO prepared above₂The nano composite film photo-anode material is used for carrying out photoelectric performance and photoelectrochemical cathode protection tests, and a double electrolytic cell system consisting of a photo electrolytic cell and a corrosion electrolytic cell is adopted. 304 stainless steel and the prepared Ag/NiS/TiO₂The nano composite material is respectively placed in the corrosion pool and the photo-anode pool. 3.5 wt% NaCl solution was placed in the corrosion cell, and 0.25M Na was placed in the photoelectrolysis cell₂SO₃As a hole trap, the naphthol film separates the electrolytes in the two cells and forms a closed loop. The reference electrode used in the experiment is a saturated calomel electrode, the electrochemical workstation is a P4000+, USA, PLS-SXE300C xenon lamp is used as a light source, and a 420 cut-off sheet is arranged at the outlet of the light source to acquire visible light to the surface of the anode. And (3) testing open circuit potential: before the experiment, a 304 stainless steel electrode is placed in 3.5 wt% NaCl solution to be soaked for 2 hours to reach an electrochemical stable state, the 304 stainless steel electrode is connected with a photoanode through a lead and then connected to a working electrode clamp of an electrochemical workstation, a saturated calomel electrode is connected with a reference electrode clamp, and the potential change of the 304 stainless steel relative to the saturated calomel electrode is observed by switching on and off light. Testing the photocurrent density: placing an ammeter with zero resistance on the surfaces of the photo-anode and the 304 stainless steel, short-circuiting the reference electrode and the counter electrode, testing the real current density of the reference electrode and the counter electrode under a non-polarized condition, connecting the 304 stainless steel electrode to the ground wire position of an electrochemical workstation, connecting the photo-anode with a working electrode clamp, and observing the change of the photo-current density on the surface of the 304 stainless steel by switching on and off light.

For the Ag/NiS/TiO prepared above₂And carrying out an ultraviolet-visible diffuse reflection test on the nano composite film photo-anode material to obtain an ultraviolet-visible diffuse reflection spectrum.

The basic principle of the invention is as follows:

NiS is a semiconductor material with narrow forbidden band width, the forbidden band width is only 1.24eV, the utilization rate of visible light is high, and the NiS is a composite TiO₂The ideal material of the material. It is compounded to TiO₂Surface of nano wire, notOnly the pure TiO can be effectively reduced₂The forbidden band width of the photo-induced electron-hole pair can enlarge the response range to visible light, increase the utilization rate of light and effectively improve the separation rate of the photo-induced electron-hole pair. The deposition of noble metal Ag can not only improve TiO due to its surface Schottky effect₂The utilization rate of light can also effectively reduce the recombination rate of photo-generated electron-hole pairs, improve the photoelectric conversion capability and effectively improve the photo-generated cathode protection performance of the nano composite material. Firstly, adopting a dipping-deposition method to compound NiS nano particles to TiO₂The Ag nano particles are compounded on the surface of the nano material by adopting a photo-reduction method, so that the TiO is greatly enhanced₂The cathode protection effect on 304 stainless steel. When light irradiates Ag/NiS/TiO₂When the surface of the nano composite material is coated, the Ag nano particle conduction band potential is negative to NiS, and the NiS conduction band potential is negative to TiO₂So that the electron flow is substantially Ag → NiS → TiO₂→ 304 stainless steel. When light irradiates Ag/NiS/TiO₂When the surface of the nano composite material is coated, the Ag nano particles have surface plasma resonance effect and can quickly generate photoproduction electrons, TiO₂And NiS is excited by light, so that photo-generated electrons rapidly transit from a valence band to a conduction band position. Because the Ag conduction band potential is more negative than the NiS conduction band potential, electrons on the Ag nano particle conduction band rapidly jump to the NiS conduction band; similarly, NiS conduction band potential ratio TiO₂The potential of the conduction band is more negative, so electrons on the NiS and Ag conduction bands are rapidly enriched to TiO₂The photo-generated electrons generated in the process reach the surface of the 304 stainless steel through the titanium substrate, and the enriched electrons participate in the oxygen reduction process of the cathode of the 304 stainless steel, so that the cathode reaction is reduced, the dissolution reaction of the anode of the 304 stainless steel is inhibited at the same time, and the purpose of protecting the cathode of the 304 stainless steel is achieved. Due to Ag/NiS/TiO₂Due to the formation of the heterojunction electric field of the nano composite material, the conduction band potential of the nano composite material is pulled to a more negative position, and the cathode protection effect on 304 stainless steel is more effectively improved. In the presence of Na in the reaction system₂SO₃Hole trapping agent, Ag, NiS nanoparticles and TiO₂The holes generated in the valence band can rapidly form polysulfides with the hole traps. Due to the presence of the hole trapping agentThe recombination probability of the photogenerated electrons and the holes is reduced, and the capability of the nano composite material for generating electrons is further improved. Good cathodic protection can be provided for 304 stainless steel coupled thereto. Thus, under visible light irradiation, Ag/NiS/TiO₂The photo-anode effectively reduces the corrosion rate of 304 stainless steel and shows good photo-cathode protection effect, namely through Ag, NiS and TiO₂The formed nano composite film can effectively improve the photoproduction cathode protection effect of the film on metal.

The invention has the advantages that:

the invention combines NiS and Ag nano-particles with TiO₂The nano wire is compounded, not only the TiO is enlarged₂The response range to light effectively improves the utilization rate of sunlight, reduces the recombination rate of photo-generated electrons and holes, reduces the electrode potential of metal, and obviously improves TiO₂The cathode protection effect on 304 stainless steel. The method specifically comprises the following steps:

1. the Ag/NiS/TiO of the invention₂The nano composite film photo-anode material forms a heterojunction electric field at the interface, so that TiO₂The absorption range of light is expanded from an ultraviolet region to a visible region, the separation rate of photo-generated carrier pairs is greatly improved, the photoelectric conversion capability is enhanced, the utilization rate of sunlight is effectively improved, the initial state of the nano composite material can be still maintained after the nano composite material is recycled for 4 times, and the stability is good.

2. The Ag/NiS/TiO of the invention₂The nano composite film photo-anode material has AgNO when the NiS nickel dipping-deposition ring times are 6₃When the photoreduction concentration is 0.1M, the prepared Ag/NiS/TiO₂The nano composite material can provide the best cathodic protection for 304 stainless steel, and compared with a saturated calomel electrode, the protection potential reaches-925 mV and the protection current reaches 410 mu A/cm²This condition provides the best cathodic protection for the 304 stainless steel to which it is coupled.

3.Ag/NiS/TiO₂The surface of the nano composite material is uniform and compact, and NiS and Ag nano particles are uniformly compounded to TiO₂The composite NiS and Ag nano particles on the surface of the nano wire have higher purity and no other impurities are introduced.

In conclusion, the Ag/NiS/TiO prepared by adopting the dipping-deposition method and the photoreduction method₂When the nano composite film is used as a photo-anode, the TiO is greatly improved₂The cathode protection effect on 304 stainless steel is an excellent anticorrosion protection material.

Drawings

FIG. 1 is a schematic diagram of the preparation of Ag/NiS/TiO₂Schematic process of nanocomposite.

Fig. 2 is a schematic diagram of an experimental apparatus for measuring changes in a photoelectric potential.

FIG. 3 is a schematic diagram of an experimental apparatus for measuring the photo-induced current density.

FIG. 4 shows that under the irradiation of visible light and in the dark state, the coupling of 304 stainless steel and NiS is performed for different times of dipping-deposition (a) and the coupling of 304 stainless steel and AgNO are performed for different times₃Graph of open circuit potential change of the nanocomposite prepared in (b) at concentration. Wherein the abscissa is time(s), the ordinate is electrode potential (V vs. sce), on indicates turning on the power supply, and off indicates turning off the light source.

FIG. 5 shows that under the irradiation of visible light and in the dark state, the coupling of 304 stainless steel and NiS is performed for different times of dipping-deposition (a) and the coupling of 304 stainless steel and AgNO are performed for different times₃Graph of photocurrent density change of the nanocomposite prepared in (b) at concentration. Wherein the abscissa is time(s) and the ordinate is current density (. mu.A/cm)²) On means power on and off means light off.

FIG. 6 shows pure TiO provided in example 1 of the present invention₂Nanowire, composite NiS, Ag nanoparticles under optimal conditions Scanning Electron Microscopy (SEM).

FIG. 7 shows AgNO with a NiS dipping-depositing time of 6 times according to example 1 of the present invention₃Ag/NiS/TiO obtained at a concentration of 0.1M₂Elemental areal distribution profile of the nanocomposite.

FIG. 8 shows AgNO with a NiS dipping-depositing number of 6 according to example 1 of the present invention₃The Ag/NiS/TiO is obtained when the concentration is 0.1M₂X-ray photoelectron spectrum of the nanocomposite.

FIG. 9 shows a schematic view of a drawing of example 1 of the present inventionPrepared TiO thus obtained₂Nanowire, NiS/TiO prepared under optimal conditions₂Nanocomposite, Ag/NiS/TiO₂Ultraviolet-visible diffuse reflectance pattern of the nanocomposite.

FIG. 10 shows Ag/NiS/TiO provided in example 1 of the present invention₂A photoelectrochemical corrosion resistance mechanism diagram of the nano composite material under the irradiation of visible light.

Detailed Description

The invention is further illustrated with reference to the following examples and figures, without thereby restricting the content of the invention.

The composite film structure of the invention is that NiS and Ag nano particles are deposited on TiO₂On the surface of the nanowire. The Ag/NiS/TiO of the invention₂The nano composite film photo-anode material forms a heterojunction electric field at the interface, so that TiO₂The absorption range of light is expanded from ultraviolet region to visible region, and when the material is used as photoanode material for cathodic protection, the material is compared with TiO₂In terms of materials, the separation rate of photo-generated electrons and holes is greatly improved, the photoelectric conversion capability is enhanced, the utilization rate of sunlight is effectively improved, the electrode potential of 304 stainless steel is obviously reduced, the corrosion rate is reduced, and the protection effect of a photoelectrochemical cathode is enhanced.

Furthermore, the invention combines the advantages of the narrow NiS band gap, the surface Schottky effect of the Ag nano particles and the photogenerated carriers in the TiO₂The characteristic of fast transmission in the nanotube is combined, so that not only TiO is expanded₂The response range to light effectively improves the utilization rate of sunlight, obviously reduces the recombination rate of photo-generated electrons and holes, reduces the electrode potential of metal, and obviously improves TiO₂The cathode protection effect on 304 stainless steel can be used in the field of cathode protection of metal materials.

Ag/NiS/TiO₂The preparation of the nano composite film photo-anode material (refer to fig. 1) comprises the following steps:

pretreatment of a titanium substrate: firstly, cutting a titanium sheet with the purity of 99.9 percent and the thickness of 0.1mm into the size of 30mm multiplied by 10mm, and then polishing each surface for 100 times by 2500-mesh sand paper to be used as a growth substrate of the composite film; secondly, in turnUltrasonically cleaning the sample with acetone, absolute ethyl alcohol and distilled water for 10min, 10min and 30min respectively, and blow-drying for later use; thirdly, the titanium sheet is put into the mixed solution (NaOH: Na) at the temperature of 85 DEG C₂CO₃：H₂O is 5: 2: 100) soaking for 90min, taking out, and cleaning with distilled water; finally, in HF solution (HF: H)₂Etching for 1min in the ratio of O to 1:5), taking out, sequentially cleaning with acetone, absolute ethyl alcohol and distilled water, and drying for later use.

TiO₂Preparing the nano wire: rapid preparation of TiO on the surface of a titanium sheet by a one-step anodic oxidation method₂A nanowire. The anode oxidation adopts a traditional double-electrode system, a titanium sheet is used as an anode, and a platinum electrode is used as a counter electrode. Firstly, a titanium sheet is clamped by an electrode clamp and put into 400mL of 2M NaOH solution, the current of a direct current power supply is regulated to be stabilized at about 1.3A, the temperature of the solution is kept at 80 ℃, the anode is oxidized for 180min, then the titanium sheet is taken out, washed by acetone, absolute ethyl alcohol and distilled water in sequence, naturally dried for later use, finally put into a muffle furnace, the temperature is set to be 450 ℃, calcined for 120min, taken out and put into a dust-free dryer for later use, and TiO can be obtained on the surface of the titanium sheet₂A nanowire.

NiS/TiO₂Preparing a nano composite film: firstly, dissolving 0.03M nickel nitrate in ethanol, and dissolving for 20min under magnetic stirring to prepare an ethanol solution of nickel nitrate; secondly, preparing a 0.03M methanol-water mixed solution of sodium sulfide (the volume ratio of methanol to water is 1: 1); then, the surface is supported with TiO₂Putting the titanium sheet of the nanowire into an ethanol solution of nickel nitrate, taking out after 2min, quickly washing for 1min by using a pure ethanol solution, and naturally drying; then putting the titanium sheet into a methanol-water mixed solution of sodium sulfide, taking out after 4min, quickly washing for 1min by using the methanol-water mixed solution, and naturally drying; finally, setting different deposition cycle times of 2, 4, 6 and 8 respectively, putting the mixture into a muffle furnace vacuum system, setting the temperature to be 380 ℃, calcining for 20min, cooling to room temperature and drying to obtain NiS/TiO with different deposition times₂A nano composite film material.

For NiS/TiO with different deposition times₂The nano composite film material is subjected to performance characterization, and the result tableWhen the optimal deposition frequency of MinNiS is 6 times, NiS/TiO₂The performance of the nano composite film material is optimal; then, the next operation was performed under the condition that the deposition number of NiS was 6.

Ag/NiS/TiO₂Preparing a nano composite film: ag nano particles are loaded on NiS/TiO by adopting a photo-reduction method₂NiS/TiO prepared by depositing NiS for 6 times on the surface of the nano composite film₂The nano composite material is respectively placed in AgNO of 0.01M, 0.05M, 0.1M and 0.2M₃Irradiating the solution for 30min by using ultraviolet light, taking out a sample, washing the surface of the sample by using deionized water, and naturally drying the sample to obtain Ag/NiS/TiO nanoparticles with different Ag nanoparticle loads₂A nanocomposite film.

Ag/NiS/TiO with different Ag nano-particle loading₂The nano composite film material is subjected to performance characterization, and analysis shows that the composite film material is AgNO₃When the concentration of the solution is 0.1M, the prepared Ag/NiS/TiO₂The nanocomposite film has the best performance.

For Ag/NiS/TiO₂And (3) characterizing the nano composite film: for Ag/NiS/TiO₂Characterization of the nanocomposite films mainly includes field emission scanning electron microscopy (FSEM), energy spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis). Wherein, the field emission scanning electron microscope adopts NOVA NANOSE EM 450 produced by FEI company of America, the accelerating voltage is 1kV, the spot size is 2.0, a CBS probe is selected, and secondary electrons and back scattering electrons are received to analyze the appearance; the energy spectrum adopts OxFORD X-MaxN50 produced by Oxford instruments science and technology Limited, the accelerating voltage is 15kV, the spot size is 3.0, and qualitative and quantitative analysis is carried out by characterizing characteristic X rays; the X-ray photoelectron spectrum adopts ESCALB 250Xi produced by Thermo Fisher Scientific company in America, the analysis adopts contaminated carbon (-284.8 eV) as sample binding energy to charge correction, the excitation power is 150W, the excitation source is monochromatic Al K alpha (1486.6eV), a fixed energy-passing mode is adopted, the full-scanning range is 0-1600eV, the energy-passing is 50eV, the step width is 1.0eV, the narrow scanning energy-passing is 20eV, and the step width is 0.05 eV; UV-visible diffuse reflectance Cary 5000, manufactured by Varian, USA, as BaSO₄As the background, the scanning range is 10-80 deg.

For Ag/NiS/TiO₂And (3) carrying out photoelectric performance test on the nano composite film:

pretreatment of 304 stainless steel: the 304 stainless steel used for the experiment had a composition (wt.%) of 0.08C, 1.86Mn, 0.72Si, 0.035P, 0.029S, 18.25Cr, 8.5Ni, and the remainder was Fe. 304 stainless steel of 10mm × 10mm × 10mm was cut out and sealed in epoxy resin, and the working surface of the electrode was 10mm × 10 mm. And (3) polishing the surface of the substrate by using 2400-mesh silicon carbide abrasive paper until the surface is smooth, cleaning the surface by using absolute ethyl alcohol, then carrying out ultrasonic treatment in water for 5min, and putting the substrate into a drying dish for later use.

Open circuit potential and photocurrent density testing: 304 stainless steel and the prepared Ag/NiS/TiO₂The nano composite material is respectively placed in the corrosion pool and the photo-anode pool. 3.5 wt% NaCl solution was placed in the corrosion cell, and 0.25M Na was placed in the photoelectrolysis cell₂SO₃As a hole trap, the naphthol film separates the electrolytes in the two cells and forms a closed loop. The reference electrode used in the experiment was a saturated calomel electrode, the electrochemical workstation was a P4000+, USA, PLS-SXE300C xenon lamp as the light source, and a 420 cut-off sheet was placed at the exit of the light source to capture visible light to the anode surface. And (3) testing open circuit potential: before the experiment, a 304 stainless steel electrode is placed in 3.5 wt% NaCl solution to be soaked for 2 hours to reach an electrochemical stable state, the 304 stainless steel electrode is connected with a photoanode through a lead and then connected to a working electrode clamp of an electrochemical workstation, a saturated calomel electrode is connected with a reference electrode clamp, and the potential change of the 304 stainless steel relative to the saturated calomel electrode is observed by switching on and off light (see figure 2). Testing the photocurrent density: and placing an ammeter with zero resistance on the surfaces of the photo-anode and the 304 stainless steel, short-circuiting the reference electrode and the counter electrode, and testing the real current density of the reference electrode and the counter electrode under the electrodeless condition. Then the 304 stainless steel electrode is connected to the ground position of the electrochemical workstation, the photo anode is connected with the working electrode clamp, and the change of the photocurrent density on the 304 stainless steel surface is observed by switching on and off the light (see figure 3).

For Ag/NiS/TiO in example 1₂The cathodic protection performance of the nanocomposites was analyzed and fig. 4 shows a graph of the open circuit potential change of 304 stainless steel coupled nanocomposites under visible illumination and dark conditions. WhereinGraph (a) shows the effect of the NiS dip-deposition times on the open circuit potential and graph (b) shows AgNO during photoreduction₃Influence of concentration on open circuit potential. As can be seen from the graph (a), NiS/TiO is at the moment of turning on the lamp after NiS is compounded₂The open circuit potential of the nano composite material coupled with 304 stainless steel is obviously reduced and is more negative than that of a pure titanium dioxide nano wire, which shows that the compounding of NiS generates more electrons and improves TiO₂The photo-generated cathode protection effect on 304 stainless steel; however, at the moment of light shielding, the open circuit potential rapidly rises to the stainless steel open circuit potential, indicating that NiS has no energy storage effect. The effect of the dip-deposit times on the open circuit potential was also observed in graph (a), where the potential reached-550 mV relative to the saturated calomel electrode, with the nanocomposite potential being significantly more negative than the other conditions, when the number of deposits was 6. It can be seen that NiS/TiO compounds are formed when the number of depositions is 6₂The nanocomposite can provide the best cathodic protection for 304 stainless steel coupled thereto. As can be seen from the graph (b), at the moment of the light-on, Ag/NiS/TiO₂The open circuit potential of the 304 stainless steel coupled with the nano composite material is obviously reduced, and the open circuit potential is obviously higher than that of pure TiO after Ag nano particles are deposited on the surface₂Nanowire, NiS/TiO₂The potential of the nano composite material is more negative, which shows that the deposition of Ag nano particles obviously improves TiO₂The cathodic protection effect of (1). At the moment of keeping out of the sun, the open circuit potential rises rapidly, and compared with a saturated calomel electrode, the open circuit potential can reach-580 mV at most, but is obviously lower than the open circuit potential (-180mV) of 304 stainless steel, which indicates that under the dark state condition, the composite material can still provide cathode protection of nearly 400mV for 304 stainless steel, and after Ag particles are deposited on the surface, the nano composite material has an obvious energy storage effect. Panel (b) shows AgNO at the same time₃Influence of concentration on open circuit potential when AgNO₃At the concentration of 0.1M, the potential of the electrode reaches-925 mV relative to the potential of saturated calomel electrode, and after 4 times of cyclic use, the potential of the electrode is still maintained at the first use level, which indicates that the nano composite material has very good stability. It can be seen that when AgNO is used₃When the concentration is 0.1M, the obtained Ag/NiS/TiO₂The nanocomposite may be coupled thereto304 stainless steel provides the best cathodic protection. TiO is irradiated by visible light and the deposition frequency of NiS is increased₂The NiS loaded on the surface of the nanowire is gradually increased, more active sites of the NiS are excited to generate electrons at the moment, and the photoinduced potential is reduced; however, when too many NiS nanoparticles are deposited on the surface, the excitation is reduced, which is not favorable for light absorption. After Ag particles are deposited on the surface, the generated electrons can be rapidly transferred to the surface of 304 stainless steel due to the plasma resonance effect of the surface, so that a very good cathode protection effect is generated; however, when the amount of Ag particles deposited on the surface is too large, a recombination point is provided for the photo-generated carrier pair, which is not favorable for the generation of photo-generated electrons. In summary, AgNO when the deposition times of NiS is 6₃At a concentration of 0.1M, Ag/NiS/TiO₂The nanocomposite can provide the best cathodic protection for 304 stainless steel coupled thereto.

For Ag/NiS/TiO in example 1₂The cathodic protection performance of the nanocomposites was analyzed and fig. 5 shows the photocurrent density variation between 304 stainless steel and the nanocomposite under visible light and no light conditions. Wherein, the graph (a) shows the influence of the NiS dip-deposition times on the photocurrent density, and the graph (b) shows AgNO during the photoreduction process₃The effect of concentration on photocurrent density. The magnitude of the photocurrent density is indicative of the separating ability of the photo-generated electron-hole pairs, with a greater photocurrent density being indicative of greater separating ability of the photo-generated electron-hole pairs. As can be seen from the graph (a), at the instant of turning on the lamp, NiS/TiO₂The photocurrent density of the nano composite material is rapidly increased and is positive than that of pure TiO₂The significant enlargement of the nanowires indicates that electrons are flowing from the nanocomposite through the electrochemical workstation to the 304 stainless steel surface. When the NiS dipping-deposition times are 6 times, the photocurrent density reaches 220 mu A/cm²Is TiO₂Nanowire generated photocurrent density (32 muA/cm)²⁾6.8 times of the total weight of the powder. As can be seen from the graph (b), Ag/NiS/TiO occurred at the instant of turning on the lamp₂The photocurrent density between the nanocomposite and 304 stainless steel is significantly higher than that of pure TiO₂And NiS/TiO₂A nanocomposite material. FIG. b shows AgNO in the photo-reduction process₃Influence of concentration of (2) on photocurrent Density when AgNO₃At a concentration of 0.1M, the photocurrent density reached 410. mu.A/cm²Is TiO₂Nanowire generated photocurrent density (32 muA/cm)²) 12.8 times of that of NiS/TiO₂1.8 times of the nanocomposite. This is because Ag/NiS/TiO₂A heterojunction electric field is formed at the interface of the nano composite material, so that the photo-generated electrons and the holes are more easily separated. As described above, AgNO when the number of impregnation-deposition of NiS is 6₃At a concentration of 0.1M, Ag/NiS/TiO₂The photocurrent density between the nano composite material and 304 stainless steel reaches 410 mu A/cm²The potential reached-925 mV relative to the saturated calomel electrode, which provides the best cathodic protection for 304 stainless steel coupled thereto.

For Ag/NiS/TiO in example 1₂The surface topography of the nanocomposite was analyzed and FIG. 6 shows pure TiO₂Scanning Electron Microscope (SEM) images of nanowires, composite NiS, Ag nanoparticles under optimal conditions. The diagrams (a) and (b) show pure TiO prepared by one-step anodic oxidation₂The nano wires are uniformly distributed on the surfaces of the nano wires, the structures are mutually closed, and the pore diameters are uniform; graphs (c) and (d) are TiO of composite NiS nano particles when the NiS dipping-deposition times is 6 times₂As seen in an electron microscope picture, the composite NiS nano particles are relatively uniform and have larger particle size, and some can obviously observe the TiO nano particles laid on the space position of the nano wires₂The nanowires are clearly visible; the graphs (e) and (f) are AgNO₃At the concentration of 0.1M, the compound is compounded to NiS/TiO₂The scanning electron microscope image of the nano composite material shows that the Ag nano particles are obviously deposited on the surface of the composite material and are uniformly distributed, and the diameter of the Ag nano particles is about 10 nm. In conclusion, NiS and Ag nano particles are successfully compounded to TiO₂The surface of the nanowire.

For Ag/NiS/TiO in example 1₂The surface topography of the nanocomposite was analyzed and FIG. 7 shows AgNO for a NiS dip-deposit number of 6₃Ag/NiS/TiO prepared at a concentration of 0.1M₂Elemental areal distribution profile of the nanocomposite. As can be seen from the figure, the presence of Ti, O, Ni, S and Ag elements was detected by the spectrum.The contents of Ti and O are the most, the contents of Ni and S are approximately the same, but the contents of Ni and S are obviously less than the contents of Ag, which shows that the quantity of Ag nano particles compounded on the surface of the material is more than that of NiS; the distribution of each element surface is relatively uniform, which shows that NiS and Ag nano particles are uniformly compounded to TiO₂The surface of the nanowire.

For Ag/NiS/TiO in example 1₂The surface state of the nanocomposite was analyzed, and FIG. 8 shows that the number of impregnation-deposition times of NiS was 6 and AgNO₃The Ag/NiS/TiO is obtained when the concentration is 0.1M₂The X-ray photoelectron spectrum of the nanocomposite, wherein the graph (a) is a full spectrum, and the rest is a high-resolution spectrum of an element. As can be seen from the full spectrogram of the graph (a), the nano composite material detects absorption peaks of Ti, O, Ni, S and Ag elements, and proves that the five elements exist, and the detection result is consistent with the energy spectrum detection. The unwanted peaks in plot (a) are carbon elements corrected for sample binding energy charge; FIG. b is a high resolution energy spectrum of Ti, the absorption peaks of 2p orbitals of Ti are respectively at 459.32 and 465eV, and the two absorption peaks correspond to Ti2p_3/2And Ti2p_1/2Can prove that the valence of titanium is Ti⁴⁺Corresponding to this experiment should be TiO₂Ti in (1); FIG. d shows the high resolution spectrum of Ni, with a total of four 2p orbital absorption peaks, and the absorption peaks at 856 and 873.5eV corresponding to Ni2p_3/2And Ni2p_1/2Orbitals, where the absorption peaks are derived from NiS, the absorption peaks at 881 and 863eV are derived from nickel nitrate and are brought by the nickel nitrate reagent during sample preparation; FIG. e shows the high resolution spectrum of S, the 2p orbital absorption peaks of S are respectively at 161.5 and 168.1eV, and the two absorption peaks correspond to S2p_3/2And S2p_1/2The orbital absorption of (1), which can be shown to be that of the NiS compound, the absorption peaks at 169.2 and 163.4eV are derived from the reagent Na₂S; the graph (f) is a high resolution energy spectrum of Ag, the 3d orbital absorption peaks of Ag are respectively located at 368.2 eV and 374.5eV, and the two absorption peaks correspond to Ag3d_5/2And Ag3d_3/2The orbital absorption of (2) can prove that the Ag nano particles exist in the state of simple substance Ag. In summary, the components of the nanocomposite are mainly Ag, NiS and TiO as tested by X-ray photoelectron spectroscopy₂Therefore, the successful composition of NiS and Ag nano particles to TiO can be further proved₂The surface of the nanowire.

For Ag/NiS/TiO in example 1₂The optical absorption of the nanocomposite was analyzed, and fig. 9 shows the prepared TiO₂Nanowire, NiS/TiO prepared under optimal conditions₂Composite material, Ag/NiS/TiO₂Ultraviolet-visible diffuse reflectance pattern of the nanocomposite. As can be seen from the figure, TiO₂The absorption threshold of the nanowires is about 390nm, and the absorbed light is mainly concentrated in the ultraviolet region. In TiO₂After NiS and Ag nano particles are compounded on the surface of the nanowire, the absorption of light is expanded to a visible region, and meanwhile, the absorption of ultraviolet light by the nano composite material is obviously enhanced, so that the narrower the forbidden band width is, the lower the electron transition energy barrier is, and the higher the light utilization rate is. In NiS/TiO₂After the Ag nano particles are compounded on the surface, the absorption intensity and the wavelength of light are not obviously increased, the main reason is caused by the surface plasma resonance effect of the Ag nano particles, and the TiO can not be obviously improved like compounding NiS nano particles with narrow forbidden band width₂The absorption wavelength of the nanowire. As described above, in TiO₂After the NiS and Ag nano particles are compounded on the surface of the nano wire, the optical absorption performance of the nano wire is obviously enhanced, the absorption range of light is expanded from an ultraviolet region to a visible region, the utilization rate of sunlight is increased, and the photoelectric conversion capability of the material is improved.

For Ag/NiS/TiO in example 1₂The action mechanism of the nanocomposite was analyzed, and FIG. 10 shows Ag/NiS/TiO₂A photoelectrochemical corrosion resistance mechanism diagram of the nano composite material under the irradiation of visible light. According to Ag, NiS nanoparticles and TiO₂The potential distribution of the conduction band and the valence band provides a feasible corrosion resistance mechanism diagram. As the conduction band potential of the Ag nano particles is negative to NiS and the conduction band potential of NiS is negative to TiO₂So that the flow of electrons is approximately Ag → NiS → TiO₂→ 304 stainless steel. When light irradiates the surface of the nano composite material, the Ag nano particles have surface plasma resonance effect and can quickly generate photoproduction holes and electrons, TiO₂And the NiS is excited by the light,the photo-generated electrons will rapidly transit from the valence band to the conduction band position. Because the conduction band potential of Ag is more negative than that of NiS, electrons on the conduction band of Ag nano particles can rapidly jump to the NiS conduction band; similarly, NiS conduction band potential ratio TiO₂The potential of the conduction band is more negative, so electrons on the NiS and Ag conduction bands can be rapidly enriched to TiO₂Finally, the generated photo-generated electrons reach the surface of the 304 stainless steel through the titanium substrate, and the enriched electrons participate in the oxygen reduction process of the 304 stainless steel cathode, so that the cathode reaction is reduced, the 304 stainless steel anode dissolution reaction is simultaneously inhibited, and the purpose of protecting the 304 stainless steel cathode is achieved. Due to Ag/NiS/TiO₂Due to the formation of the heterojunction electric field of the nano composite material, the conduction band potential of the nano composite material is pulled to a more negative position, and the cathode protection effect on 304 stainless steel is more effectively improved. In the presence of Na in the reaction system₂SO₃Hole trapping agent, Ag, NiS nanoparticles and TiO₂The holes generated on the valence band can be rapidly combined with Na₂SO₃Forming polysulfides. Due to the existence of the hole trapping agent, the recombination probability of photogenerated electrons and holes is reduced, the photoelectric conversion capability of the nano composite material is further improved, and good cathodic protection can be provided for 304 stainless steel coupled with the nano composite material.

The Ag/NiS/TiO of the invention₂Making TiO from nano composite film photo-anode material₂The light absorption range of the photo-anode is enlarged from an ultraviolet region to a visible region, so that the photo-anode not only can inhibit the corrosion of metal, but also has excellent photoelectric conversion effect, and can play a good photo-generated cathode protection effect on 304 stainless steel as a photo-anode.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.